Nano-channel gate-all-around (“GAA”) metal oxide field effect transistors (“MOSFET”) have been shown to offer performance gains over fin channel MOSFETs (“FinFETs”). Improvements in areas such as off-state leakage and on-state drain current have been demonstrated by the GAA MOSFET. Currently, fabrication of GAA nano-wire structures often involve epitaxial growth of alternating layers of sacrificial material and channel material on a substrate. Special etchants of high selectivity are then used to remove the underlying sacrificial material, thereby creating a suspended channel above the surface of the substrate. However, the cost for implementing epitaxial deposition is generally high, and the search for a suitable etchant of high selectivity is not always easy. Moreover, the epitaxial sacrificial layer may inevitably induce strain related defects in the nano-scale channel.
Accordingly, a gate-all-around (GAA) structure and fabrication method thereof are proposed.